细胞期刊(Cell)2014-04-29 5:06 PM

洞穴昆虫的雌性阴茎,雄性阴道及其相关进化 Female Penis, Male Vagina, and Their Correlated Evolution in a Cave Insect

重点
•洞穴昆虫属Neotrogla的雌性拥有复杂精致的阴茎状器官 
•雌性阴茎是雌性对雄性的插入器官 
•我们检测了雌性阴茎和雄性生殖器之间的相关进化 

Highlights
•Females of the cave insect genus Neotrogla have an elaborate penis-like organ
•The female penis acts as an intromittent organ and anchors the female to the male
•Correlated evolution is detected between the female penis and male genitalia

研究总结
性别特异性的精密性在动物中很常见并吸引了包括达尔文在内众多生物学家的关注。
我们普遍认为性选择加速了性别特异精密性的演变。由于生殖细胞的快速补充速率,雄性一般具有比雌性更高的潜在生殖率和最佳交配率。因此性选择在雄性身上起着强烈作用,这导致了雄性生殖器的快速进化和多样化。雄性生殖器有时用作交配过程起性冲突时雌性用来强制夹持的装置。与此相反,雌性生殖器则通常很简单。我们在此揭示了巴西洞穴昆虫属Neotrogla插入器官的(性别)颠倒现象(Psocodea :Prionoglarididae)。雌性具有高度复杂的阴茎状结构gynosome,而雄性则缺乏插入器官。该gynosome结构具有物种特异精密性,例如具有许多能与简单雄性生殖器室内物种特异性袋囊吻合的刺状物。在长时间的交配过程中(大约40〜70小时),大量潜在的营养精液经由gynosome从雄性体内移出。Neotrogla相关性生殖器进化可能是与雌性争夺精液的反向性选择所驱动。我们还未在性别角色颠倒的动物中发现类似现象。
Summary
Sex-specific elaborations are common in animals and have attracted the attention of many biologists, including Darwin. It is accepted that sexual selection promotes the evolution of sex-specific elaborations. Due to the faster replenishment rate of gametes, males generally have higher potential reproductive and optimal mating rates than females. Therefore, sexual selection acts strongly on males, leading to the rapid evolution and diversification of male genitalia. Male genitalia are sometimes used as devices for coercive holding of females as a result of sexual conflict over mating. In contrast, female genitalia are usually simple. Here we report the reversal of intromittent organs in the insect genus Neotrogla (Psocodea: Prionoglarididae) from Brazilian caves. Females have a highly elaborate, penis-like structure, the gynosome, while males lack an intromittent organ. The gynosome has species-specific elaborations, such as numerous spines that fit species-specific pouches in the simple male genital chamber. During prolonged copulation (∼40–70 hr), a large and potentially nutritious ejaculate is transferred from the male via the gynosome. The correlated genital evolution in Neotrogla is probably driven by reversed sexual selection with females competing for seminal gifts. Nothing similar is known among sex-role reversed animals.

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唧唧堂调查:巴西发现雌性有阴茎雄性有阴道昆虫 性交达70小时 

4月27日消息,人类有变性行为,在动物界也神奇的有变性的生物。据外国媒体报导,科学家在巴西东部发现了4种住在洞穴里、属于Neotrogla种属的独特昆虫(Neotrogla意即雌性有阴茎,雄性有阴道。这些昆虫当中,雌性个体拥有非常可观的阴茎,但雄性却拥有非常狭小、类似阴道的开口 。 

当双方交配时是由女方采主动,雌性个体会将直立而多刺的性器官插进雄性类似阴道的狭小开口里吸取精子。这种复杂的生态结构称为雌性阴茎(gynosome),主要功能是吸收精子和富含营养的精液。 

更惊人的是,进入雄性阴道后,双方可以连续性交40至70小时!而且如果雄性因为想主动结束而反抗,生殖器还会被割伤! 

因为一旦插入后,雌性昆虫的阴茎就会膨胀,并且会伸出许多刺勾住,让两者紧密的固定在一起。当研究人员试图将它俩分开时,雄性的腹部从胸腔被扯下,但性器结合的部分却依然完整。 

研究人员认为,这种交配方式会为雌性提供食物和精液,因此时间更久的交配对它们是有利的。这种古怪的昆虫为生物学家提供了新的机会,来验证两性矛盾以及演化的观点。 

日本北海道大学的吉泽和德( Kazunori Yoshizawa)博士说:“尽管性别角色反转在好几种动物身上都出现过,但Neotrogla却是唯一连插入式性器官也可以反转的例子。”上述该研究发表在《当代生物学》(Current Biology)期刊。 

罗德里戈·弗雷拉是一名洞穴生物学家,现就职于巴西拉夫拉斯联邦大学。不久前,弗雷拉及其研究团队在巴西一处极度干燥的洞穴里发现一个名为“尼欧托格拉”(Neotrogla)新昆虫属,其包含的四种昆虫均有一个奇特的生物结构,即雄性和雌性昆虫的生殖器官颠倒。 

“‘尼欧托拉格’属昆虫是自然界第一个两性生殖器官颠倒的案例。”据弗雷拉介绍,这种雌性昆虫的生殖器官很大,长度约为总身长的1/7,交尾时,雌性昆虫把阴茎状的生殖器官插入雄性昆虫的“阴道”里,它们的交尾时间可达到惊人的40至70小时。 

弗雷拉和日本北海道大学教授吉泽一典将上述发现合著成论文,发表于最新一期的美国科学期刊《当代生物学》。“这一发现展现出一种全新的生物进化结构。”吉泽一典表示,“类似的生物进化极其罕见,几乎可以与昆虫翅膀的起源比肩而论。” 

吉泽一典还解释道,洞穴里自然资源极其匮乏,但雄性昆虫能产出营养丰富的精液,这导致雌性昆虫大幅提高交尾的频率和强度,“很有可能是雌性昆虫强迫雄性昆虫交尾,而在自然界中,强迫性交通常是雄性的专属功能”。 

吉泽一典说,他们将继续研究雄性昆虫如何应对强迫交尾,除此之外,他们还在巴西洞穴里发现了一些其他的新物种。“巴西拥有超过15万处洞穴,在那里,我们很有可能会有更多新发现。” 

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